This invention is directed in general to electrophotographic reproduction apparatus, and more particularly to a multi-mode electrophotographic apparatus capable of reproducing electronically generated information or information obtained optically from a document.
Electrophotographic reproduction apparatus typically reproduce information by exposing a uniformly charged photoconductive surface to a light image of information. The light image modifies the uniform charge on the photoconductive surface so as to form a charge pattern, or latent image, on the surface corresponding in an image-wise configuration to the information to be reproduced. Pigmented marking particles, exhibiting a charge of opposite polarity to that of the latent image charge pattern, are brought into contact with the photoconductive surface and adhere to the areas of the surface where the charge pattern exists to develop the latent image and form a transferable image. Thereafter, the transferable image is transferred to a receiver member and permanently fixed to such member by heat and/or pressure to form the desired reproduction.
Exposing of the photoconductive surface has primarily been accomplished by one of two methods. One method of photoconductive surface exposure involves forming a light image of a document (generally referred to as optical copying). In this method, light is directed from a lamp assembly at a document with the light reflected from (or transmitted through) the document being directed through a lens unit into focus on the photoconductive surface. The light from the lamp may illuminate the entire document at one time (referred to as flash exposure), or may be passed through a slit and moved relative to the document to illuminate successive line segments of the document (referred to as scan exposure).
The second method of photoconductive surface exposure involves the use of an electronically controlled light emitting component (generally referred to as nonimpact printing), such as a laser or a plurality of light emitting didoes (LED's). The light emitting component is turned on and off to expose the photoconductive surface in a line-by-line fashion to form a desired charge pattern thereby creating a latent image on the surface corresponding to an image-wise configuration to the information to be reproduced. The information to be reproduced is electronically generated and is used to control the turning on and off of the light emitting component.
While the above described photoconductive surface exposure methods have, in practice, proven to be difficult to incorporate in a single reproduction apparatus, several attempts at their combination have been shown in the literature. Particularly, U.S. Pat. Nos. 4,046,471 (issued Spet. 6, 1977, in the name of Branham et al); 4,355,882 (issued Oct. 26, 1982, in the name of Snelling); and 4,471,175 (issued Oct. 16, 1984, in the name of Snelling) show multi-mode electrophotographic reproduction apparatus which provide for optical copying of documents by reflected light exposure and printing of electronically generated information by light emitting component exposure. The apparatus disclosed in the U.S. Pat. No. 4,046,471 utilizes a complex laser scanner assembly as the light emitting component for electronically generated information printing and margin erase in the optical copying mode. The apparatus disclosed in the U.S. Pat. No. 4,355,882 also utilizes a complex laser scanner assembly. This apparatus also requires an asynchronous photoconductive belt drive to accommodate for differences in speeds necessary to accomplish laser scanning and electrophotographic processing. The apparatus disclosed in the U.S. Pat. No. 4,471,175 utilizes a simplified LED assembly as the light emitting component. However, it requires a complex prism/lens mechanism for focusing both the LED produced image and the optically produced image at the photoconductive member surface.